Best quality option to convert 1080p mkv to 720p mkv

[carlmart]

The title says it all. Which is the best quality options to convert a 1080p mkv to 720p mkv?

I've found several ways to do it: Ripbot, AutoMKV, MeGUI. But I am not sure about the final quality I will get from each.

Any suggestions?

[Soopafresh]

They all use the same high quality h264 encoder (x264.exe) so the difference won't be very much.

[carlmart]

I started a first try with Ripbot, and apparently it was going to take many hours to convert, also using both cores in my computer. So I will do it overnight. AutoMKV was also slow, so probably the blame is on the x264.

[Atak_Snajpera]

I wouldn't blame x264! Blame your sloooooow cpu! BTW. Nothing is for free. High quality = advanced algorithms enabled in x264 which require cores*Mhz.
Dual-core is a low end machine for video encoding. For example Intel i7 cpus are the best cpus for this task at the moment. Especially the new one with 6-core Beast!

[carlmart]

You're certainly right. But I don't need so much power right now, this is an exception.

Going i7 now would mean changing cpu, mobo and memos: too much money. I might consider a quad cpu first for my setup.

[carlmart]

Another question related to x264.

What happens with the audio file? Do I have to demux the original ac3 from the 1080p mkv? Will it be in sync?

I ask this because I've had cases where the audio file, when converting to DVD files which is not the case here, did go out of sync. H264 files do seem to have such problems, I think.

Edit:

Well, things did not turn out too fine. Movement is faster than it should and audio is out of sync. I wonder what should I put on the setup to make it work. My guess is it's probably a setup thing. I would also like size to be larger than it is, as that might provide me a better quality.

Where can I find instructions on how to set things up?